That's not right!" exclaims Todd Mavieus, resting his bones one recent night in a wooded glade in upstate New York. He has already hiked more than half the famed Appalachian Trail that runs up the eastern United States from Georgia to Maine and he doesn't want to hear that it might be about to get longer.

You can't blame him. Mavieus, 57, a retired computer programmer, has walked 1,411 miles since striking out from Georgia on 7 April and he's wondering if he has it in him to go the additional 767 miles that remain between him and the trail's end in Maine. His hiking name – all "thru-walkers" on the trail are given one – is Overload. But his problem today is not his pack. It's his food-poisoning.

Completing the AT, as they call it, in one foot-blistering slog is to hikers what conquering Everest is to mountaineers. As anyone who has read A Walk in the Woods will know, the travel writer Bill Bryson tried it and famously failed. So how dare someone come along and suggest it could be extended – and into another country, no less. But why stop there? How about threading it through other continents as well?

Welcome to the imaginings of Dick Anderson, a former state commissioner for natural resources in Maine. With a group of geologist chums, he first began dreaming back in 1994 of taking the AT beyond its official buffers at the peak of Mount Katahdin in his state and into the maritime provinces of eastern Canada. The ridges along the Canadian coastline, they reasoned, were directly related to the Appalachians.

Labelled the International Appalachian Trail, the extension through New Brunswick, Nova Scotia, Prince Edward Island and Newfoundland is now more or less in place with a few gaps to be filled in. "It's the only place where you can hike a long-distance trail and see whales and icebergs," says Anderson.

But things are about to get even more crazy (in the minds of folk like Mavieus, at least). Anderson and his team are proposing taking the IAT in a grand loop all the way around the North Atlantic.

Again, geology provides the reasoning. Hundreds of millions of years ago, the continental plates of America and Europe collided before drifting apart again to their current positions, with the ocean between them. But it was that impact that threw up not just the Appalachians in the US, but also the ranges of Western Europe and north Africa, including the Atlas Mountains of Morocco and the windblown peaks of the Orkneys.

The logic is pretty simple then. Before he is done, Anderson, who is now in his 76th year, would like to see the Appalachian Trail running from Georgia to Morocco, not just by way of the US and Canada, but also taking in Greenland, Iceland, Ireland, Scotland, Norway, France, Portugal and Spain.

His group is already reaching out to officials or hiking associations in all of those countries. Delegations of IAT proponents are heading to Morocco and Norway in the next couple of months. Last June, Anderson himself, with some friends, visited Scotland at the invitation of the British Geological Survey in Edinburgh and some of them splintered off to meet officials in Northern Ireland. Earlier this summer, the West Highland Way in Scotland was officially co-designated part of the International Appalachian Trail.

It all makes complete sense to Anderson. "We want people to think beyond borders; there are no borders in nature," he explained in a telephone interview from Maine. "There are great social connections here, and there are great connections of the mountains." He points out that many of the people who live in the eastern provinces of Canada are descended from immigrants from the British Isles.

His enthusiasm has been matched in Scotland. "We have been close neighbours on ancient continents, which shared in the building of the Caledonian-Appalachian mountain chain and were only recently – in geological terms – separated by the opening of the North Atlantic," Hugh Barron of the Geological Survey said recently. It was Barron who hosted Anderson last year, taking him on a walk up Ben Nevis.

Anderson says he has just heard second-hand of French support for bringing the IAT through parts of Brittany, and Greenland formally opened a chapter of the IAT association this June. "The amount of interest that has been shown just in the last couple of months has been amazing to us," he says.

The original Appalachian Trail came into being in the mid-1930s. It was cut by enthusiasts through the thick woods and craggy ranges of 14 American states. White blazes on the trunks of trees keep hikers from getting lost, and there are roughly 250 primitive shelters along the way where they can spend nights protected from the elements and from predators, including bears. The route is managed by the National Parks Service and a charity called the Appalachian Trail Conservancy.

What Anderson is proposing does not especially thrill the Conservancy. "We do not support any of the talked-about extensions of our responsibilities for a number reasons," Brian King, its associate director, said last month. "We and our volunteers have all we can handle right now."

On the trail itself, the first reactions to the project are ones of consternation. Morocco seems an awful long way from the Fahnestock State Park in upstate New York, where Mavieus has shuddered to a painful halt this sunny evening. The trail happens to bisect the park, famous for its cool lake and beaches, and the rangers who manage it are proud to offer thru-walkers sites in their campground free of charge.

Evan Thompson, one of the Fahnestock rangers, smiles at the idea of the trail running through Europe. "It would be great for walkers over there to have what we have here," he says. But he can imagine the reaction of those ending the original trail only to be told that actually they've hardly started. "Haven't we done everything already? What did we do wrong here?" he imagines them asking.

Thompson, a big fan of the Bryson book, is quick to raise another not-so-minor obstacle: isn't it tricky to open a walking trail that will be frequently interrupted by stretches of ocean? "How would they get from Greenland to Iceland," he wants to know. "That would seem like a big problem to me."

Mavieus has a more philosophical difficulty. "The trail is so unique to the US that I think there would just be a lot of resistance to calling this the Appalachian Trail. I'm guessing those mountains in Scotland are not called the Appalachians, am I right? This is a historic landmark and you don't just alter landmarks."

But he is joined in the campsite this evening by Bird, the walking name for 23-year-old Donald Doolittle, a student from North Carolina, who has similarly dedicated half a year to walking the Trail.

Listening to the story of how it might one day reach Morocco, his eyes brighten. "That sounds like such an amazing idea," he declares. "I think more people should experience what we are experiencing. That's something I can easily see myself getting behind."

Even if support builds quickly for the project, there is as yet no deadline for completing it. Anderson says that maintenance and the financing of the new trail would be left to each jurisdiction it runs through. In some instances whole new sections of would have to be built. Sometimes, existing trails would be co-labelled as belonging to the International Appalachian Trail, as has happened in western Scotland.

Finally, of course, hikers would have to be encouraged to embrace it. Already, following the path in eastern Canada involves taking connecting journeys by train and ferry, for example to make it over to Prince Edward Island. Reportedly, only 14 hikers have so far made it all the way from Maine to the end of the Canadian section at Crow Head in Newfoundland.

Jumping all the gaps en route to Morocco via territories as far flung as Donegal and Norway would require ever greater dedication and travelling ingenuity. But Anderson is the first to admit that walking the International Appalachian Trail will be a different sort of experience. "The stretches of water don't matter really," he explains, "because the International Appalachian Trail is a journey more than it is a walk."